Particle Size Distribution of Lunar Soil

Meteorite impact on the lunar surface produces a consistent, broadly graded soil. In this note, the geotechnical and geological systems are compared to characterize lunar soil. In geotechnical terms, the lunar soil particle size distribution is described as sandy silt/silty sand, well-graded. In geologic terms, it is described as very fine sand, very poorly sorted, nearly symmetrical, and mesokurtic. Because of its broad particle size distribution, lunar soil may be internally erodible.     

Magnetite Particle Size Distribution and Pellet Oxidation

Oxidation of magnetite pellets is commonly performed to prepare strong pellets for ironmaking. This article presents a contribution to quantitative understanding of fundamental pellet oxidation kinetics, based on measured oxidation kinetics of magnetite particles and pellets. The commonly observed “plateau” oxidation behavior is confirmed to be consistent with the effect of very large differences in magnetite particle sizes in the concentrate from which pellets are produced. The magnetite particles range in size from less than a micron to several tens of a microns; changing the size distribution by inert sintering of pellets decreases both the plateau level of oxidation and the specific surface area, in ways that are compatible with an assumed Rosin-Rammler magnetite particle size distribution.     

钛粉粒度对Ti-Mo吸气剂性能的影响

以3种不同粒度的活性Ti粉制备Ti-Mo吸气剂. 研究了Ti粉粒度及烧结温度对吸气剂性能的影响. 对样品进行了表面形貌的观察和比表面积、孔隙度的测试, 分析了粒度影响Ti-Mo吸气剂性能的原因. 结果表明, 活性Ti粉的粒度影响吸气剂的比表面积和孔隙度, 从而影响Ti-Mo吸气剂的吸气性能. Ti粉粒度过大或过小, 制备的Ti-Mo吸气剂的孔隙度和比表面积均较低, 吸气性能较差;平均粒度适中的Ti粉制备的吸气剂孔隙度和比表面积均较高, 吸气性能最佳.     

Microstructural and Mechanical Characteristics of Porous Irons Produced with Small Particle Size Corn Starch

Powder Metallurgy and Metal Ceramics - The space holder technique was widely used in manufacturing high melting-point porous metals. Corn powders with a smaller size (11.4 μm on average) than...     

粉末粒度分布对烧结钕铁硼微观结构形成的影响

烧结钕铁硼永磁材料是用粉末冶金方法制造的,其生产环节中的每道工序对磁体的最终性能都有相当大的影响。从微观结构上看,磁性能的高低主要是由于具体的微观结构不同造成的。而其中制粉环节粉末的粒度分布对最终产品微观结构的形成具有非常大的影响。采取一组实验,以探讨不同的粉末粒度分布对产品微观结构形成的影响。     

Particle Size Distribution and Metal Content in Street Sediments

Sediments that had accumulated during the winter season, and which were left at the surface when the snow had melted, were studied with regard to physical and chemical characteristics. The investigation was carried out in the city of Lule?, which is located in northern Sweden. Sediment samples were collected in the city center and in a housing area at streets with different traffic loads. The results showed that the amount of the sediments at a street surface was evidently affected by the presence of a sidewalk. The street with a sidewalk accumulated much more sediment than the street without a sidewalk did. Both of these streets had approximately the same traffic load. The sidewalk also affected the particle size distribution. The content of heavy metals in the sediments varied with the traffic load and the area type. The highest concentration of cadmium, lead, and zinc was found in the street with the highest traffic load.     

粒度对石油焦硫含量分布及煅烧脱硫的影响研究

通过库伦滴定法分别测定不同粒度石油焦的硫含量及其煅烧后的硫含量。结果表明,粒度对不同硫含量石油焦中硫含量有影响,且差异较大,硫含量2.54%石油焦可筛分出硫含量2.25%石油焦(粒径-0.5mm),3.35%石油焦可筛分出硫含量2.33%石油焦(粒径-0.15mm),硫含量5.98%石油焦筛分的作用较小;粒度对石油焦脱硫具有明显差异,粒度+0.5mm的2.54%石油焦脱硫效果较好,粒度+1mm的3.35%石油焦脱硫效果较好,整个粒度范围内5.98%石油焦脱硫效果差异不大。     

真空气雾化参数对粉末粒度及形貌的影响研究

对雾化压力、雾化气体温度等雾化参数对粉末粒度、形貌的影响进行了研究。试验结果表明,雾化压力在2.3~3.2MPa范围内对粉末粒度影响不大,当雾化压力超过3.5MPa时,粉末粒度开始变细小。雾化气体温度对粉末粒度影响最大,较高的雾化气体温度有利于获得较细小的粉末。     

金属熔化热的粒度效应

本文根据热力学原理推导出高分散度金属的熔化热与其粒度的关系式,并从一系列金属的有关热力学量数值计算证明:高分散度金属粉末的熔化热小于其非分散状态的熔化热。     

Effects of Particle Size on Nitridation Kinetics of Manganese Powder

Isothermal thermo-gravimetric analysis was applied to investigate the nitridation kinetics of manganese powder with different particle sizes at 800,900 and 1 000℃.The apparent activation energy and nitridation kinetics equations of manganese powder with different particle sizes were obtained from unreacted shrinking core model and Arrhenius formula.It was found that the nitridation mechanism was controlled by interfacial chemical reaction.The apparent activation energy and the apparent rate constant of nitridation reaction were affected by particle sizes.With the decrease of particle size,the apparent activation energy decreased whilst the apparent rate constant increased.It was suggested that the refinement of the manganese powder contributed to the increase of molar surface energy,which accounted for the lower apparent activation energy.     

重质MnCO3粉末的粒度分布和颗粒形貌

测定了不同视密度下ＭｎＣＯ３粉末的粒度分布，揭示了重质ＭｎＣＯ３粒度分布的特性，用ＳＥＭ展现了颗粒的形貌。     

铜冶炼企业重金属污染物粒径分布特征研究

对某铜冶炼企业铜冶炼有组织源和无组织源进行监测研究,并利用AERMOD空气质量模型对企业重金属污染物扩散情况进行模拟,通过对铜冶炼企业环境空气质量浓度预测值与监测值的拟合结果来验证铜冶炼企业废气中重金属污染物粒径分级的合理性。结果表明,污染源粒径分级参数的选择对铜冶炼企业重金属污染物的空气质量浓度计算结果有显著影响;当采用"双闪"工艺的铜冶炼企业重金属污染物铅、铜、砷、锌粒径参数质量百分比为25%、质量中位径为8μm时,AERMOD空气质量模型能较好地模拟该企业重金属污染物的扩散。     

铅冶炼企业重金属污染物粒径分布特征研究

对某铅冶炼企业的有组织源和无组织源进行监测研究,利用AERMOD空气质量模型模拟重金属污染物扩散,通过拟合废气中重金属污染物的预测值与监测值,研究铅冶炼企业废气中重金属粒径的分布特征。     

粉末粒径对真空等离子体喷涂钛涂层的影响

粉末粒径是影响等离子体喷涂涂层结构和性能的主要因素之一。本文采用四种不同粒径分布的钛粉,通过真空等离子体喷涂（VPS）工艺在不锈钢基体上制备了粗糙多孔的钛涂层,研究了粉末粒径与钛涂层表面粗糙度、气孔率和结合强度间的关系。结果表明：在粉末熔融状况良好的情况下,不同粒径分布的钛粉制备的涂层结构均较均匀;钛涂层的表面粗糙度和气孔率随粉末粒径的增大而增大,涂层结合强度随粉末粒径增大而减小。     

灼烧温度对镨钕二元氧化物粒度和形貌影响的研究

以氯化镨钕溶液为原料液,分别用草酸、碳酸氢铵和碳酸钠为沉淀剂制备镨钕草酸盐和碳酸盐,在900℃~1500℃范围内不同灼烧温度下制备出镨钕二元氧化物,利用粒度仪和扫描电镜进行测试,研究了灼烧温度对稀土氧化物的粒度和形貌特征的影响;结果表明,灼烧温度的提高对中位粒径D50和粒度分布R变化影响不同,改变灼烧温度对镨钕二元氧化物的形貌影响较大。     

钴酸锂粒度控制对产品性能的影响

介绍了钴酸锂生产过程中,通过控制合成炉温度提高了产品的粒度均匀性,同时产品物理性能得到改善,克容量提高2 mAh/g。     

基于粒度分配曲线的Falcon离心选矿机干涉沉降机理研究

基于粒度分配曲线研究矿物颗粒在Falcon离心选矿机中的干涉沉降机理,以分选粒度d50和可能性偏差Ep作为分配率曲线的评价指标,分析Falcon离心选矿机在不同的操作条件下对粒度分配率和分选效率带来的影响。根据离心选矿机分选过程中固相浓度变化和速度变化的非稳态过程以及不同粒度的沉降情况,建立Falcon离心选矿机的干涉沉降模型,采用有限差分方法求解对流扩散方程。通过试验在不同的反冲水、离心力、进矿浓度条件下验证了模型的有效性,通过仿真分析,获得了不同的操作条件对粒度分配率和分选效率带来的影响结果。     

氧化铝种分过程的粒度分析

用粒数衡算的方法对氧化铝生产种分过程氢氧化铝粒度分布进行了分析,通过计算得到各种分槽产品氢氧化铝的晶体生长速率和净粒子生成数,由此推测了氧化铝实际生产过程中成核、生长、附聚过程发生的位置及生产条件。并分析了晶体生长速率与种分进行时间之间的关系。     

激光粒度分布仪检测细碳化钨粉方法

随着微细、超细甚至纳米级钨粉、碳化钨粉的生产,粉末粒度分布的检测方法也随之发生重大变革,从传统的沉降法、显微镜法等逐步演化成了现代的激光粒度分布仪检测方法,然而现在的激光粒度分布仪检测方法仍然存在一些问题,尤其是检测不稳定,检测出较多的粗大颗粒或团聚问题。笔者对激光粒度分布仪的检测方法进行了摸索,找到其检测不稳定的原因,并提出了检测稳定的方法。     

磁铁矿粉粒度对球团矿预热焙烧性能的影响

 研究了3种不同粒度的超细磁铁精矿粉,粒度小于0.044 mm的矿粉质量分数在89%以上。试验研究了其制备的球团矿的焙烧性能。试验结果表明,铁精矿粉粒度越细,球团矿在最佳焙烧制度下获得的抗压强度也越高,但适宜的预热温度也越低,而所需预热及焙烧时间也越长。在对生球孔隙率测试研究的基础上发现,精矿粒度越细,生球孔隙率越小,氧化变得越困难,需要较长的预热时间,而预热温度太高,表层易形成致密层,导致球团矿强度下降;在对适宜的焙烧制度下焙烧的球团矿的FeO含量测定结果表明,对于焙烧球团矿,随矿粉粒度的变细,其FeO含量则越高,表明氧化条件变差,需较长的焙烧时间。